GEOLOGY and the Rock Cycle

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GEOLOGY and the Rock Cycle
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GEOLOGIC PROCESSES

• The earth is made up of a core, mantle, and crust
  and is constantly changing as a result of
  processes taking place on and below its surface.
• The earths interior consists of
• Core innermost zone with solid inner core and
  molten outer core that is extremely hot.
• Mantle solid rock, under which is the
  asthenosphere that is melted pliable rock.
• Crust Outermost zone which underlies the
  continents. (Lithosphere)

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Spreading center
Ocean trench
Collision between two continents
Oceanic tectonic plate
Oceanic tectonic plate
Plate movement
Plate movement
Tectonic plate
Oceanic crust
Oceanic crust
Subduction zone
Continental crust
Continental crust
Material cools as it reaches the outer mantle
Cold dense material falls back through mantle
Hot material rising through the mantle
Mantle convection cell
Mantle
Two plates move towards each other. One is
subducted back into the mantle on a falling
convection current.
Hot outer core
Inner core
Fig. 15-3, p. 337
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INTERNAL GEOLOGIC PROCESSES

• Huge volumes of heated and molten rock moving
  around the earths interior form massive solid
  plates that move extremely slowly across the
  earths surface due to convection currents.
• Tectonic plates huge rigid plates that are moved
  with convection cells or currents by floating on
  magma or molten rock.

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Folded mountain belt
Volcanoes
Abyssal plain
Abyssal floor
Oceanic ridge
Abyssal floor
Abyssal hills
Trench
Craton
Continental slope
Oceanic crust (lithosphere)
Abyssal plain
Continental shelf
Continental rise
Mantle (lithosphere)
Continental crust (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
Fig. 15-2, p. 336
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Earth

• orbit 149,600,000 km (1.00 AU) from Sun
• diameter 12,756.3 km
• mass 5.972e24 kg
• Earths layers (depths in km)
• 0- 40 Crust
• 40- 2890 Mantle
• 2890-5150 Outer core
• 5150-6378 Inner core

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Earth

• Earths mass (measured in 1024 kg)
• atmosphere 0.0000051
• oceans 0.0014
• crust 0.026
• mantle 4.043
• outer core 1.835
• inner core 0.09675

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Earths Interior

• Core is made up mostly of iron/nickel
• Temperatures in core reach 7500 K
• The crust is primarily quartz.
• Taken as a whole, the Earth's chemical
  composition (by mass) is
• 34.6 Iron 2.4 Nickel
• 29.5 Oxygen 1.9 Sulfur
• 15.2 Silicon 0.05 Titanium
• 12.7 Magnesium

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The Earths Major Tectonic Plates
Figure 15-4
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Major Plates

• North American Plate
• South American Plate
• Antarctic Plate
• Eurasian Plate
• African Plate
• Indian-Australian Plate
• Nazca Plate
• Pacific Plate

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Plate Movement

• The extremely slow movements of these plates
  cause them to grind into one another at
  convergent plate boundaries, move apart at
  divergent plate boundaries and slide past at
  transform plate boundaries.

Figure 15-4
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Fig. 15-4, p. 338
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EURASIAN PLATE
NORTH AMERICAN PLATE
ANATOLIAN PLATE
CARIBBEAN PLATE
JUAN DE FUCA PLATE
CHINA SUBPLATE
ARABIAN PLATE
PHILIPPINE PLATE
AFRICAN PLATE
PACIFIC PLATE
SOUTH AMERICAN PLATE
NAZCA PLATE
INDIA-AUSTRALIAN PLATE
SOMALIAN SUBPLATE
ANTARCTIC PLATE
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Fig. 15-4a, p. 338
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Trench
Volcanic island arc
Craton
Transform fault
Lithosphere
Rising magma
Lithosphere
Subduction zone
Lithosphere
Asthenosphere
Asthenosphere
Asthenosphere
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Fig. 15-4b, p. 338
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Convergent Plate Boundary

• Two plates pushed together
• Oceanic Continental Subduction Zone
• Oceanic Oceanic Trench
• Continental Continental Mountain Range

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Divergent Plate Boundary

• Plates moves apart from one another
• Oceanic plates form oceanic ridges

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Transform Faults

• Plates slide and grind past one another along a
  fracture in the lithosphere

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Benefits of volcanoes, earthquakes, and tsunamis

• Geological
• Recycle rock and earths crust
• Form minerals
• Ecological
• Speciation (due to isolation)
• Maintaining atmosphere thus climate
• Enrich soils more food

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Geologic Time Scale

• 4.6 billion years ago Earth believed to have
  formed, hot ball of rock
• 3.9 billion years ago rainstorms
• 3.5 billion years ago oceans, first living
  organisms

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Geologic Eras

• Precambrian Era 4.6 billion years ago- 545
  million years ago
• 87 of Earths history
• Prokaryotes dominated
• First eukaryotes appeared 1.5 billion years ago
• Simple multicellular organisms in seas
• Paleozoic Era 545 million years ago 248
  million years ago
• Explosion of life
• Many types of invertebrates in shallow seas
• Early earliest vertebrates
• Middle amphibians
• Later reptiles

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Geologic Eras

• Mesozoic Era 248 million years ago 65 million
  years ago
• Triassic mammals made first appearance
• Jurassic age of dinosaurs
• Cretaceous radiation of mammals and evolution of
  flowering plants
• Plate Tectonics continental shift
• Cenozoic Era 65 million years ago now
• Mammals flourish
• Primates evolve
• Extinctions affect diversity
• Modern human species evolved 200,000 years ago

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EXTERNAL GEOLOGIC PROCESSES

• Surface processes
• Based largely on energy from the sun and gravity
• Tends to wear down Earths surface and produce a
  variety of landforms by the buildup of eroded
  sediment
• Erosion
• Weathering

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Wearing Down and Building Up the Earths Surface

• Weathering is an external process that wears the
  earths surface down.

Figure 15-6
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EROSION

• Process by which material is dissolved, loosened
  or worn away from one part of the earths surface
  and deposited in other places
• Streams are most important agents of erosion

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MINERALS, ROCKS, AND THE ROCK CYCLE

• The earths crust consists of solid inorganic
  elements and compounds called minerals that can
  sometimes be used as resources.
• Mineral resource is a concentration of naturally
  occurring material in or on the earths crust
  that can be extracted and processed into useful
  materials at an affordable cost.

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Nonrenewable mineral resources

• Fossil fuels (oil, natural gas, coal)
• Metallic minerals (Al, Cu, Fe)
• Nonmetallic minerals (sand, gravel, limestone)

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Minerals and their Uses

• Metals

• Nonmetals

• Al- building, cans
• Steel- building
• Cu- conductor, electronics
• Mn, Co, Cr- used in alloys
• Pt- catalytic converters

• Sand- glass, concrete, bricks
• Gravel- roadbeds
• Limestone- roadbeds, natural buffer
• Phosphate salts- fertilizers

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US consumption

• 8 of world population but use 75 of metals on
  earth
• Uses cars, engines, appliances, weapons,
  satellites

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ROCK

• A very slow chemical cycle recycles three types
  of rock found in the earths crust
• Sedimentary rock (sandstone, limestone). Formed
  from sediment of pre-existing rocks that are
  weathered and eroded
• Metamorphic rock (slate, marble, quartzite).
  Formed when pre-existing rock is subjected to
  high temperatures or pressure
• Igneous rock (granite, pumice, basalt). Formed
  from cooled magma at or below earths surface

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Erosion
Transportation
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Melting
Metamorphic rock Slate, marble, gneiss, quartzite
Fig. 15-8, p. 343